Telephone apparatus.



PATENTED NOV. 27, 1906.-.

H. J. ROBERTS. TELEPHONE APPARATUS.

APPLICATION FILED 0OT.1. 1903.

MIMI/Ill '1 fifdaeaa as:

THE NORRIS PirERs cm, WASHINGTON, n, c.

UNITED STATES PATENT OFFICE.

HOMER J. ROBERTS, OF EVANSTON, ILLINOIS.

TELEPHONE APPARATUS.

Specification of Letters Patent.

Patented Nov. 27, 1906.

Original application filed September 18, 1902, Serial N 0. 123,968.Divided and this application filed October 1,1903. Serial To all whmn itmay concern:

Be it known that I, HOMER J. ROBERTS, a citizen of the United States,residing at Evanston, in the county of Cook and State of Illinois, haveinvented certain new and useful Improvements in Telephone Apparatus, ofwhich the following is a specification.

This invention relates to improvementsin telephone apparatus, and refersmore specifically to improvements in selective party-line telephonesystems.

Among the salient objects of the present invention are to provide asystem in which the operator at central may select and call any one ormore of the subscribers belonging to a given party-line at will andwithout signaling or otherwise giving notice to the remaining partiesbelonging to said line; to

provide a system in which the operator at central may give to any one ortwo parties upon a given party-line the exclusive use of the lines, soas to prevent interference by other parties; to provide means in asystemof the character last mentioned whereby the parties excluded are alsocut out of the talking-circuit, so that surreptitious listening isprevented; to provide a system in which grounding connections andconnections across the lines are cut off or opened in the act ofselecting the arties, so that the main lines are electrical y intactfrom central to the subscriber called, thus enabling a large number ofsubscribers to be placed upon the same party-line without seriouslyimpairing the effectiveness of the working currents; to provide in asystem of the character referred to means whereby two subscribersbelonging to the same party-line may be properly connected tocommunicate with each other by the operator at central and at the sametime the remaining parties locked out or excluded;

to provide means for effectively clearing or.

restoring the instruments to normal condition after use andindependently of or with out the cooperation of the subscriber; toprovide means whereby the operator at central may have such control overthe several subscribers instruments that a subscriber may cut off atwill and during the use by him of his instrument, thus enabling theoperator at central to prevent arbitrary or unreasonable retention ofcircuit connections by subscribers, and in general to provideimprovements in the construction and arrangement of instrumentalities ina system of the character referred to.

To the above ends the invention consists in the matters hereinafterdescribed, and more particularly pointed out in the appended claims andwill be readily understood from the following description, referencebein had to the accompanying drawings, in whic Figure l is adiagrammatic view of one embodiment of the invention. Fig. 2 is a detailsectional view showing the construction of the operators switch-keyadapted for use in connection with the system shown in Fig. 1. Fig. 3 isa fragmentary detail showing the upper end of one of the armature-leversshown in Fig. 1 and the end of the cooperating armature-lever, thelatter shown in section taken on line 2 2 of Fig. 1.

Referring to Fig. 1, H and I respectively designate selectiveinstruments located at different subscribers stations, and J and Kdesignate as a whole so much of the corresponding subscribers tele honesets as is necessary to an understan in of the invention. M designates akey mechanism located at central, and N a battery connected therewith. Rand L designate the right and left main lines, leading from central tothe respective subscribers stations. Describing in detail one of theinstruments H or I, 100 designates as a whole a suitable frame providedat each end with standards, as 101 102. 103 designates a primary magnetwhich is pro vided with a double winding. Upon the standard 102 ispivotally mounted an armature-lever 104, which is arranged to extendhroizontally above the magnet 103 and carries an armature 105, adaptedto cooperate therewith. Above the armature-lever 104 is arranged toextend a second and longer armature-lever 106, which, as herein shown,is

rovided with a downturned extension 107, fiaving slotted engagement withthe same pivot which carries the armature-lever 104, as indicated at108, and is supported from the armature-lever 104 by means of anupstanding contact-plate 109, having aninclined upper end 110 and twocontact PIOJGCUOHS or pomts 111 and 112, respectively. Upon thearmature-lever 106 are mounted insulated contact-plates 113 114 inposition to cooperate with said contact-pomts 111 and 112. Thearmature-lever 106 is further connected with the armature-lever 104 bymeans of a link 115, which is rigidly connected with the lower lever andextends upwardly through a suitable aperture 116 in the upper lever andterminates in a hooked portion 117, which serves to limit the distanceto which the armature-levers may be separated while per- I mitting themto approach each other freely.

The link forms a conductor, as will hereinafter appear, and its hookedupper end is arranged to engage a contact-plate 118, forming theterminal of a circuit, asvwill also be hereinafter described. Upon thefree end of the longer armature-lever is mounted an armature 119, whichis acted upon by a magnet 120, mounted upon a suitable support extendingout from the standard 101. Said magnet performs the function of holdingthe armature-lever 106 during the operation of certain other elementsand will therefore be hereinafter designated the holding-magnet. 121designates a third magnet, which is mounted upon the standard 101 and isarranged to actuate an armature-lever 122, which cooperates with thearmature-lever 104 in a peculiar manner, said armature 122 being to thisend arranged at right angles to the said armature-lever 104 and locatedadjacent to the swinging end of the latter. The armature 1.22 isconveniently pivoted to the base-frame, as indicated at 123, and is maderelatively broad or of plate-like'form at its upper end, as indicated indetail, Fig. 3, sald upper end being provided with an aperture 124,adapted to permit the free passage therethrough of acorrespondingly-shaped head 125, mounted upon the armature lever 104.With the upper side of the aperture 124 communicates a vertical slot126, which is of sufficient width to permit the free passagetherethrough of a reduced neck-like portion 127, which unites the head125 with the main body of the armature-lever 104. In the normal positionof the armature-lever 122 the latter stands with its slotted aperturedportion in vertical register with the neck portion 127 of thearmature-lever 104, so that the latter may rise and fall withoutaffecting the movement of the lever 122. In the normal or open positionof the lever 104 the end thereof is in horizontal register with theupper slotted end of the lever 122, and it follows, therefore,-that thearmature-lever 104 must be closed before the lever 122 is free to moveinto closed position, and, vice versa, if the lever 122 be closed whilethe armature-lever 104 is in closed position and the latter subsequentlyreleased, it will lock the lever 122 in closed position. 128 designatesa contactlever which is arranged to cooperate with the armature-lever122, said contact-lever being conveniently pivoted at one end upon thesame pivot 123 which supports the armature-lever, although insulatedfrom the latter and from the point of support and being interposedbetween the armature-lever and the proximate end of the magnet spool. 1In order to avoid interference with the polepiece of the magnet, saidcontact-lever is apertured midway of its length to pass around orembrace the pole-piece without contacting therewith. A V or expansionspring 129, interposed between the contactlever and a bracket likeextension 130 upon the magnet-spool, serves to hold or force thecontact-lever toward the armaturelever, its approach to the latter beinglimited normally by means of an adjustable contactscrew 131, threadedthrough the armaturelever and engaging a contact device .132, mountedupon the contactdever. The contact-screw 131 is insulated from thearmature-lever, as shown. A somewhat similar contact-screw 133 extendsthrough the armature-lever and engages a second contact device 134,mounted upon the contact-lever, this latter contact-screw being madeyielding between its ends, as indicated at 135, and both the screw andcontact with which it cooperates being insulated from their respectivesupports. 136 and 137 designate another pair of contact-screws mountedin a second extension 138 upon the magnet-spool and insulated therefrom,these two latter contact devices being arranged to cooperate with thecontact devices 132 and 134, respectively, at the time the contact-lever128 is forced outwardly or to the left by the closing of thearmaturedever 122. In this case also the contact-pin 137 is madeyielding between its ends, as indicated at 139. A mechanical detent isprovided lor locking the contactlever 128 in depressed position, or inthat position to which it is moved by the closing of the armature-lever122, the said detent consisting of a springdatch 140, mounted upon theunder side of the long armature-lever 106 in such position as to projectinto the path of the end of the lever 128 when said lever is depressedor forced into closedposition. Then the armature-lever 106 is released,the catch or detent 140 is withdrawn from the path of the end of thelever 128 and permits the latter to return under the action of itsspring. The armature-lever 106 has alimited rocking movement relativelyto the'armature-lever 104, so as to change the point of bearing be IIOtween said members from the contact-point 112, which engages the plate114, to the con tact-point 111, which engages the plate 113, wheneverthe lower armature-lever 104 is released, while the upper armature-leveris held in closed position. To this end a slotted extension107,hereinbefore described, is provided, and a contractile spring 141 isarranged. to connect an extension 106 of the pivoted end of thearmature-lever with a subjacent bracket 102. Upon the standard 102 thelower armature 104 is acted upon by an expansion-spring 142, interposedbetween its lower side and the upper side of the mag net-spool 103.

Next describing the construction and arrangement of a switch mechanismor connecting-key which is located at the central station and effectsthe making and breaking of the proper circuit connections for operatingthe selective instruments described, 150 designates as a whole the mainbody of the key, which is desirably constructed of insulating materialand is pivotally connected at one end upon a suitable support so as toswing in a definite plane. The pivot-bearing of said connecting-key orswitch-leveris of two-part construction, comprising an inner metallicstud 151, which is connected, by means of a conductor 152, with one sideof the battery N, and a concentric member or ring 154, insulated fromthe stud 151 and connected, by means of a suitable conductor 155, withthe opposite end of the battery N. Upon the under side of theconnecting-key are mounted three separate contact plates or buttons 156,157, and 158,- plate 157 being electrically connected with the ring 154by means of a conductor] 59, shown as conveniently embedded in the bodyof the key. Upon the upper side and at the outer end of theconnecting-key is mounted a pair of spring contact-strips, (designated160 and 161,) these contact-strips being formedintegrally with eachother to extend longitudinally of the key in opposite directions andsecured fixedly to the key at the central point by means of a suitablescrew 162. 163 and 164 designate two fixed contact devices, respectivelyadapted to cooperate with the spring contact-strips 160 and 161, thestrip 160 being arranged to stand normally in open position and to beclosed when depressed and the strip 161 being arranged to stand normallyin closed position and to be opened when depressed. The screw 162 iselectrically connected with the pivot-stud 151 of the connecting-key bymeans of a conductor 165, thereby lacing the contactstri s 160 and 161in el ectrical connection wit said stud 151.. An extension-conductor 166leads from the contact-screw 162 to a bindingscrew 167, which serves tohold. the contact device 164 in position, and from thence to and isconnected with the contact-plate 156. A resistance-coil 168 isinterposed between the securing-screw 162 and the contact-plate 156.

It will be seen from the foregoing that current entering through thestud 151 may be transmitted to the'plate 156 either with or withoutinterposed resistance, the circuit being shunted around theresistance-coil when the contact-strip 161 is in closed position, butcompelled to pass through the'resistance- I coil when said contact-stripis in open posig tion. The contact-plate 163 is connected with thecontact plate or button 158 by means of a conductor 169.

Upon a suitable base or support over which the connecting-key isarranged to sweep is mounted a continuous contact-strip 17 0, arrangedconcentrically with the pivotal axis of the connecting-key and inregister with the contact-plate 156, so that the latter forms continuousengagement therewith. 171 and 172 designate as a whole two series ofcontact-studs also mounted upon the base concentrically with the pivotalaxis of the key and respectively arranged in register with thecontact-plates 157 and 158. The contact-studs 171 and 172 are alternatedradially, the first stud of the series 172 being so located as to befirst engaged by the key when the latter is moved to the right from itsnormal or open position. The several members of each series ofcontact-studs 171 and 17 2 are connected with each other by means ofconductors 173 and 174, and one series is connected with the other bymeans of a conductor 175. The two series of studs are adapted to beconnected with the left main line through a conductor 176, and thecontinuous contact-strip 170 is likewise adapted to be connected to theright line bymeans of a conductor 177, these connections being madethrough a plug and jack, (designated,respectively, 178 and 179.)

Describing now the various circuits as they exist and are brought intouse during the operation of the apparatus, it will be seen that thesubscribers left line is normally ready for communication with centralwhen the subscribers receiver is removed from the receiverhook, thecircuit being in such case traced as follows: from the subscribersinstrument over the conductor 180,1eading to the contact-plate 118 ofthe armature-lever 106, thence through link to a back 0011- tact 181,mounted upon an upright frame member 101, and from the latter contact bya conductor 182 to the contact-screw 133 of the armature-lever 122. Fromthis contactscrew the circuit extends through contact device 134 andthence by way of awconductor 183 to the main left line. The subscriberis therefore enabled to ring central at will.

In calling the subscriber from central, the first operation is toenergize the primary magnet 103 and close the armature 104, theholding-magnet being at the same time energized and serving to retainthe armaturelever 106 in closed position after it has been drawn down bythe armature-lever 104 of the primary magnet. It may be explained atthis point that the holding-magnet 120 is made of very low resistance,so that it interposes into the line only'so much resistance as IIC isnecessary to securely hold its armature in position, and that owing tothe fact that the armature-lever is relatively long and thespring-pressure acting to open the same small said magnet may be made ofvery low resistance. i I

The circuit for energizing the primary magnet is closed when theoperator at central moves the switch-lever key so as to bring thecontactplate 156 into bearing with the contact-strip 170, which, ashereinbefore described, is connected with the sleeve or righthand sideof the main line through the conductor 177. This circuit may betraced asfollows: from ground at central through the battery to the stud 151 ofthe key over conductor 152, thence by way of conductors in the key tothe contact-plate 156 and contactstrip 170, thence to line overconductor 177 From line at the subscribers station a con ductor 184leads to and through the magnet 120, and thence a conductor 185 leads tothe contact-blade 109. From the blade 109 the circuit is throughcontact-plate 114, and thence by way of conductor 186 to and through thecoils of the primary magnet and thence to ground at 187 through aconductor 186, thus completing the circuit and energizing the twomagnets 120 and 103. The closing of this circuit draws down armature104, and with it, through the link 115, the armature-lever 106. Theclosing of armaturelever 104 opens a circuit at contact 181 and closescircuits at two contacts mounted upon the under side of thearmature-lever 104 and respectively designated 188 and 189, the formerbeing brought into bearing with a fixed contact 190 and the latter witha yield without interrupting the current which extends through this andthe holdingmagnet. This circuit it closed when the switch-lever is movedfar enough to bring the contact-plate 157 thereof into contact with thefirst stud 171, which contact is connected with the left side of mainline, as hereinbefore described. The contact-plate 158 will of coursehave made contact with stud 172, but owing to the fact that this circuitis open at contactplate 163 the circuit will remain interrupted. Theneutralizing-circuit, as it may be properly called, is an all-metalliccircuit and may be traced as follows: from battery at central over theright line the connections to contact-blade 109 are as hereinbeforedescribed, at which point the circuit divides, one branch going toground at 187 through one set of coils in the primary magnet and anotherbranch extending through the armature-lever body 104 to contact-plate189 and cooperating contact 191, thence through a conductor 192 to andthrough the other'set of windings of the primary magnet, and thence byway of a conductor 193 to the body of the armature-lever 122. The latteris at this time-resting in contact with a back-contact device 194,mounted upon and insulated from'the standard 101, and from this lattercontact a conductor 195 leads back to the left main line. From the leftmain line at central the circuit is through conductors 176 and 175 tostud 171, thence through contactplate 157 and conductor 159 to the outerpivot member 154 of the switch-key, and from the latter throughconductor 155 to the opposite side of the battery N, thus comings of theprimary magnet, the latter is deenergized and its armature moves intoopen position. In so doing the holding-magnet is not released ashereinbefore described, and accordingly the upward movement of the link115 opens the circuit extending through the same at the contact-plate118. The circuits also are opened at the contacts 188 and 189, and thepoint of bearing between the armature-lever 106 and the armature-lever104 is changed from the contactplate 114 to the contact-plate 113 byreason of the relative rocking movement hereinbefore described. Thischange in position of the various parts results in extending theright-line circuit connections through to the next subscribersinstrument of the series, the continuation being traced as follows: fromthe contact-blade 109 through the contact-plate 113, thence by way of aconductor 196 to the contact device 132, mounted upon the contact-lever128, which contact device 132 normally rests in bearing with thecontact-screw 13 1. From the latter screw a conductor 197 leads on tothe continuation of the main right line, which latter is connected withthe succeeding instrument in the same relation as with the first. Itfollows, therefore, that since the switch-lever key is in continuousengagement with the contact-strip 170 the neutralizing of the primarymagnet will result in closing the circuit to the next instrument andenergizing its primary magnet. 2

Assuming now that the second instrument in the series is the instrumentbelonging to the subscriber wanted, the next operation will be toenergize the connecting-in magnet 121 of that instrument so as to closethe bell circuit. The circuit energizing the connecting-in magnet may betraced as follows: from ground at central through the battery andseveral conductors to the spring conducting-strip 160, and from thelatter (when depressedlthrough contact 163, conductor 169, contact-plate158 to contact-button 172, thence over the left line to a branch line183 at the instrument in question, and from the latter through the coilsof the connectingin magnet 121 to the conductor 198, which leads to thecontact 190. From the contact 190 current is transmitted to contact 188,and thence by a conductor 199 to ground, thus completing the circuitfrom ground to ground. The energizing of magnet. 121 closes thearmature-lever 122 thereof and in so doing closes the circuit betweenthe contact device 132, mounted upon the lever 122 and the cooperatingcontact-screw 136. The bell-circuit thus formedis from central over theright main line to blade 109 and plate 113, to conductor 196 and to saidcontact 132, thence to contact-screw 136, and from the .latter over aconductor 180 to the righthand side of the subscribers instrument, andthence to and through the bell indicated at 200. The bell is connectedto ground at its opposite side, as indicated at 201, and it is to benoted in this connection that it is neces sary to use a biased bellwhich responds only to a direct pulsating current.

The clearing of the instrument, after the subscriber has finishedtalking is accomplished by the operator at central, who simply returnsthe switch-lever key to its normal position. This denergizes theholdingmagnet 120, whereupon the armature-lever thereof rises, thusrestoring the parts to their normal positions.

The foregoing operations are the ones which take place when theconnection is to be made between a subscriber on the partyline and oneon a different line. Obviously it is sometimes necessary to giveconnections between subscribers on the same party-line, and for thispurpose special means are necessarily provided, as will now bedescribed.

, Assuming, for instance, that the subscriber at instrument H desires tocommunicate with the subscriber at the next instrument down the line,(designated 1,) it will be necessary for central to retain the circuitconnections with the first subscribers telephone set while securing theproper connections with the subscriber at I. The subscriber at H callscentral for connection in the usual manner, and

central proceeds to make the connection as follows: The first movementof the switchkey closes the circuit through the primary magnet at theinstrument at station H, as be fore. In this instance, however, insteadof moving the switch-key to the position in which it forms contact withthe contact-stud 171 the operator at central stops when itscontact-plate 158 is in contact with stud 172, and while in thisposition depresses contactstrip 160. This energizes the connecting-inmagnet in the manner hereinbefore described, and while the contact-strip160 is thus held in closed position and the connecting-in magnetenergized central depresses the connecting-strip 161, thereby openingthe shunt around the resistance 168, or, in

other words, interposes the resistance 168 in the circuit which is atthis time maintaining the primary and holding magnets energized. Theinterposition of the resistance 168 reduces the current sufficiently torelease the primary magnet, but not the holding-magnet, whereu on thearmature lever 104 rises, thus bringing its headed end 125 oppo site andbehind the upper end portion of the armature 122. This results inlocking the latter mechanically in its closed position, so that it willbe held against opening when the circuit through the connecting-inmagnet is opened. The operator at central now permits the twocontact-strips 160 and 161 to assume their normal positions, then movesthe key on to select the next party, and does this in precisely the samemanner as though the latter party were the only one wanted. WVhile thearmature-lever 122 of the connecting-in magnet is thus mechanically heldin closed position, it will be seen that the subscriber at.instrument His connected on to the next instrument and to central by circuits, whichmay be traced as follows: from the right-hand side of his own instrumentto contact-screw 136, from the latter through contact 132 to thecontact-screw 131, thence by way of conductor 197 to the right main lineleading to the next instrument down the line. The other side may betraced from the leftside of his set through conductor 180 tocontact-screw 137 and contact device 134 and thence over conductor 183to the left main line.

It will be seen from the foregoing description that I accomplish theseveral objects of the invention set forth and provide a system whichmay be adapted to any ordinary telephone-line at a very moderate expenseand by the use of an apparatus of an extremely simple nature, andtherefore not easy to get out of repair or adjustment. It willfurthermore be seen that the details of the embodiment of the system maybe'very considerably modified without in any sense departing from thespirit of the invention, and accordingly I do not limit myself to thedetails of construction and arrangements herein shown except to theextent that they are specifically claimed.

This application is filed as a division of my prior application, SerialNo. 123,958, filed September 18, 1902.

I disclaim invention of the combination of a line broken at a series ofstations with nonpolarized electromagnet mechanism adapted to build up acircuit through any desired number of said stations and non-polarizedelectromagnetic mechanism adapted to break said circuit at saidstations.

I also disclaim invention of the combination with a central office of aseries of local stations and a discontinuous conductor extending fromthe central office to the first ing united will be electricallyconnected to the continuous conductor.

I also disclaim invention of the combination last above stated providedwith means whereby upon making a series of single contacts the localstations will be excluded one by one from telephonic connection withsaid conductors, and means whereby upon making a double contact in theseries of contacts the corresponding local station will be placed intelephonic connection with said conductors.

I claim as my invention 1. In a party-line telephone system, thecombination with a central station, a series of substations and a doubleline extending from central to and through the series of substations, ofa selector instrument at each substation, each selector having a primarymagnet and a holding-magnet, one limb of the double line extending fromcentral to and through the primary magnet of the first station-selectorand to ground, extensionsections of said limb extending from the firstsubstation to and through the primary magnet of the nextsubstationselector and to ground, and in like manner from station tostation of the succeeding stations, the other limb extending fromcentral to the first instrument and normally open at the latter andextensions of this limb from substation to substation normally open ateach instrument, and means controlled by said primary magnet whereby thedisconnected sections of each limb may be united from station to stationand other means whereby they may be united with each other at anydesired sta tion, for the purpose set forth.

2. In a party-line telephone system, the combination with a centralstation, a series of substations and a double line extending fromcentral to and through the series of substations, of a selectorinstrument at each substation, each selector having a primary magnet anda holding-magnet, one limb of the double line extending from central toand through the primary magnet of the first station-selector and toground, extension-sec tions of said limb extending from the firstsubstation to and through the primary magnet of the nextsubstation-selector and to ground, and in like manner from station tostation of the succeeding stations, the other limb extending fromcentral to the first instrument and normally open at the latter andextensions of this limb from substation to substation normally op en ateach instrument, and means controlled by said primary magnet whereby thedisconnected sections of each limb may be united from station to stationand other means whereby they may be united with each other at anydesired station, and at the same time the circuit shunted around thechief resistance of the intervening selector instruments, for thepurpose set forth.

3. In a party-line telephone system, the combination with a centralstation, a series of substations and a double line extending from centrato and through the series of substations, of a selector instrument ateach substation, each selector having a primary magnet and aholding-magnet, one limb of the double line extending from central toand through the holding and primary magnets of the selector at the firstsubstation and to ground, extension-sections of said limb extending fromthe first substation instrument to and through the holding and primarymagnets of the next substation-selector in order and to ground, and inlike manner from station to station of the succeeding stations, a doublearmature having two parts capable of movement independently of eachother controlled by each primary magnet, one member of each such doublearmature being also controlled by the corresponding holding-magnet,contact devices for uniting the sections of said limb of the linecontrolled by that member of each armature which is not controlled bythe holding-magnet and means for establishing neutralizingcircuitsthrough the primary magnets,

4. In a party-line telephone system, the combination with a line-Wireand a suitable source of current, of a series of selective instrumentseach normally inoperative connection with said line-wire,electrically-actuated means in each instrument operative to cut outfunctionally the subscribers set controlled thereby, subsidiaryelectrically-actuated mechanism for restoring the line connections of agiven subscribers set and at the same time looking his selectiveinstrument against functional movement by the cuttingout operations asto succeeding instruments,

whereby two subscribers upon the same line may be placed incommunication to the exclusion of others, and means for restoring theinstruments to normal position.

5. In a party-line telephone system, the combination with a line-wireand a suitable source of current, of a selective instrument normally inoperative connection with said line-wire and comprising a primarymagnet, an armature controlled thereby, a contact-lever actuated by saidarmature, a secondary magnet and armature, a contact-lever actuated bysaid secondary magnet, a mechanical locking device for holding one ofsaid contact-levers in a definite position, and elecoperativelyconnected with said line-wire and trically-actuated means for releasingsaid comprising a primary magnet, a signaling demechanical lockingdevice, for the purpose set forth.

6. In a party-line telephone combination with a line-wire and a suitablesource of current, of a selective instrument 5 normally in operativeconnection with said line-wire and comprising a primary magnet, anarmature controlled thereby, a contact- 1 lever actuated by saidarmature, a secondary magnet and armature, a contact-lever actuated bysaid secondary magnet, an automatically-engaging locking device forholding the contact-lever of the primary magnet in that position towhich it is shifted by the movement of the armature of said magnet,means tending to restore the armature-lever of the magnet to its normalposition, contact devices actuated by said armaturelever, and means fordisengaging said locking mechanism and restoring the parts to theirnormal positions.

7. In a party-line telephone system, the l combination with a line-wireand a suitable source of current, of a selective instrument system, themagnet, contact mature and. controlling the circuit through saidsignaling device, a second magnet of relatively low resistance, anarmature-lever actuated thereby, and means controlled by said secondmagnet for restoring parts of the in strument to normal position.

8. In a telephone system, the combination with a magnet and vibratoryarmature, of a lever mounted adjacent to said armature and yieldinglyheld in bearing with a part thereof, a spring-latch mounted adjacent tosaid con tact-lever and adapted to engage and hold the latter whenshifted in one direction by the armature-lever, circuit connectionscontrolled by said contact-lever, and means for releasing saidspring-latch.

HOMER J. ROBERTS.

Witnesses 2 ALBERT H. GRAVES, FREDERICK O. GooDwIN.

vice, an armature operated by said primary devices actuated by said ar-

